Torches

[Oz]

I have welded with oxy-acetylene for over 25 years. Having said that, for welding I usually use a stick welder or mig these days. For cutting, you just can’t beat the oxy-acetylene. I’m not sure if I chose the best tip for melting silver, gold, or inquarting but I can share with you my logic in choice. To get the same amount of heat out of a small orifice welding tip you have a greater velocity of gases coming from the tip. So I have been using a cutting tip adjusted to a reducing flame. Just make sure you don’t hit the lever to throw the extra oxy like when cutting steel or you surely will scatter your PMs everywhere.

 

[CarlClassen]

Okay that was a new experience for me! When I lit the torch for the first time It scared the beep out of me.

Lessons learned.

1. Get the lid off the borax BEFORE you turn the torch on
2. Need either bigger Stainless steel jug or need to pour from higher level
3. Goggles are good. I was happy I wore mine! Didn’t think it would get that bright.

I used the torch head on the left. Next time I’ll use the single small head on the right. I found the flame was very yellow. I was having a hard time figuring out how to get it nice and blue like in Steve’s video.

I had no idea what the lever does on the torch. The instruction booklet doesn’t help either. Thanks for clearing that up oz, markqf1. I won’t touch it.


The inquarted gold came out like pictured. Was in not hot enough? Or did I need to pour from higher up?

The crucible came out looking like crap. Can I reuse it? How do I recoat it? What did I do wrong?

When I turned off the gas cylinders I noticed that the oxygen pressure stays high but the acetylene slowly goes down. Can that mean I have a leak? I checked with soap and water before hand but didn’t find any.

Thanks for the help.

[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/Gold6K.jpg[/img]
[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/TorchHeads.jpg[/img]
[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/Cruicible.jpg[/img]

 

[Anonymous]

James,

Are you sure that is acetylene your burning? When I light my torch on acetylene only, it burns very dirty with carbon floating in the air until I kick in the oxy to get a clean burning flame. Some people even soot their molds with straight acetylene so the gold doesn’t stick when poured. If you were using compressed air with acetylene it might work, but it sounds like you are talking about a torch that operates like a plumbers propane soldering torch.

Yes, I am sure. My torch is made for it to breath air, you oxy/act is not it does not have breathers.

I do not buy oxygen, I do have a oxygen/acetylen cutting set up but never use it. It just takes up space in the truck.

 

[draftinu]

Carl, You had numerous problems somewhere. The torch tip on the right is the one you need to use, the melting dish is junk, what did you inquartate? and don't use the trigger on the torch that is for cutting metal, not melting PM's. Good luck! And be carful! :shock:

 

[Harold_V]

Okay that was a new experience for me! When I lit the torch for the first time It scared the beep out of me.

Did it pop?

I used the torch head on the left. Next time I’ll use the single small head on the right.

The head on the left appears to be a cutting tip. It is not the best choice for melting, but only because it is used in conjunction with a cutting head, which has the lever you spoke of.

I found the flame was very yellow. I was having a hard time figuring out how to get it nice and blue like in Steve’s video.

A yellow flame ( that's a reducing flame) is the result of too much fuel, and not enough oxygen. Depending on which torch body you use, you must adjust the proper valves until you get the desired flame. The pressure setting on your regulators is also critical. Start with something like 10 pounds of oxygen and 5 pounds of acetylene and see how it goes. Too much oxygen pressure is not a good idea, not even when cutting.

If you can describe your torch to some degree, I may be able to provide guidelines on pressure settings. Your welding supply house should have some literature that would be helpful as well.

A neutral flame would be desirable for melting gold. That would be a flame that has a blue cone, but displays a slight hint of yellow at the tip. The yellow is a sign of incomplete combustion of the fuel.

I had no idea what the lever does on the torch. The instruction booklet doesn’t help either. Thanks for clearing that up oz, markqf1. I won’t touch it.

The lever introduces excess oxygen, which in turn burns the preheated metal (steel) to make a cut. That type of torch body is not the best choice, although a tip of that nature is an excellent choice. There are Hoke torches available at jewelry supply houses that use just such a tip, although I'm not suggesting you should invest in one. Just a point of information.

The inquarted gold came out like pictured. Was in not hot enough? Or did I need to pour from higher up?

There is nothing about the material that looks right.

Can you tell me what you melted? Did you use copper for inquartation?

The crucible came out looking like crap.

That's a melting dish, not a crucible. They are not the same thing.

Can I reuse it?

Yes---it is not destroyed, just dirty.

How do I recoat it?

The best procedure would be to heat the dish and introduce some soda ash, which will reduce the oxides and clean the dish. Once molten, you'd stir the soda ash to assist in the cleaning process, then add some borax to increase volume. You should see some small prills of metal form, which will contain some of your values. If you have access to an assayer's cone mold, pour the flux mixture in the mold while it's quite fluid. If the dish is still quite dirty, repeat. When you are satisfied that the dish is clean, recoat it with a little borax.

Be advised, the cleaning process I mentioned dissolves a portion of your dish. Don't carry the operation too far. A clean dish, for inquarting, is not necessary. It will gradually become dark with oxides, and the flux cover getting correspondingly thicker and thicker. You can add some fresh borax to extend it's life, but it will eventually require cleaning as I prescribed. When you have exhausted a melting dish that has been used for inquartation, remember that the flux contained will have values. Do not discard the dish without going through the cleaning process I outlined.

What did I do wrong?

Hard to say. Detail what you melted, and what you used for inquartation.

A casual glance tells me that you may have melted something that should not have been melted.

When I turned off the gas cylinders I noticed that the oxygen pressure stays high but the acetylene slowly goes down. Can that mean I have a leak? I checked with soap and water before hand but didn’t find any.

It is my opinion that you have a leak. My acetylene does the same thing, so I make a habit of keeping the bottle turned off unless it's in use. I suggest you do the same. I've never found the source of my loss, and I've had my regulator(s) rebuilt.

Thanks for the help.

Better save the thanks for the time when I have helped. Not sure I have in this case, but I'd like to. Tell us more.

Harold

 

[CarlClassen]

Carl, You had numerous problems somewhere. The torch tip on the right is the one you need to use, the melting dish is junk, what did you inquartate? and don't use the trigger on the torch that is for cutting metal, not melting PM's. Good luck! And be carful! :shock:

Ok I'll switch heads. I melted a mix of 14k and 10k Gold. I added silver to inquartinate.

 

[lazersteve]

The dish looks more like a cupel to me. I use a standard melting dish or one of the larger hard white ones.

From the looks of the left over slag, there was lots of copper in the material and little or no silver (no white residue around the rim).

The color of the cooled material also does not appear to have been inquarted with silver, it typically has a silvery appearance with purple and dark colors mixed in. The texture is also wrong. The pieces should have come out more like cornflakes instead of random pieces of distorted alloy. You may be pouring the metal too fast from the looks of the material produced. Another possibility is that the metal was not fully molten.

Here's a photo of inquarted cornflakes made with silver:

[img:452:413]http://www.goldrecovery.us/images/275_inquarted.jpg[/img]

Steve

 

[CarlClassen]

Did it pop?

It was just the amount of flame that came out. I think i had the acetylene on too high. You could say it "poped"

The head on the left appears to be a cutting tip. It is not the best choice for melting, but only because it is used in conjunction with a cutting head, which has the lever you spoke of.

I've switched heads for try #2.

A yellow flame ( that's a reducing flame) is the result of too much fuel, and not enough oxygen. Depending on which torch body you use, you must adjust the proper valves until you get the desired flame. The pressure setting on your regulators is also critical. Start with something like 10 pounds of oxygen and 5 pounds of acetylene and see how it goes. Too much oxygen pressure is not a good idea, not even when cutting. .

Ok i was using a LOT less pressure. more like 3 pounds of oxygen and 4 pounds of acetyelne.

If you can describe your torch to some degree, I may be able to provide guidelines on pressure settings. Your welding supply house should have some literature that would be helpful as well.

The torch looks exactly like Steve's from what I can see. I'll post a pic. Its a Power Fist Harris Style Medium Duty Welding & Cutting Kit. God now that i rereading the instruction I see that since I'm not using the cutting tip i don't install it at all.

A neutral flame would be desirable for melting gold. That would be a flame that has a blue cone, but displays a slight hint of yellow at the tip. The yellow is a sign of incomplete combustion of the fuel.

Ok

There is nothing about the material that looks right.

Can you tell me what you melted? Did you use copper for inquartation?

Well it was 10k and 14k with silver used for inquartination. The material I got looks gold with purple.

That's a melting dish, not a crucible. They are not the same thing.

Oh, whats the difference?

You should see some small prills of metal form, which will contain some of your values. If you have access to an assayer's cone mold, pour the flux mixture in the mold while it's quite fluid.

I don't have an assayer's cone mold. Can i pour the flux mixture into water to extract the material that way?

I really appreciate the help.


Torch without cutting tip
[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/Picture026.jpg[/img]


Torch with cutting part taken off
[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/TorchBottom.jpg[/img]

Part I'll attach to above
[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/Picture027.jpg[/img]

Regulators
[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/RegulatorHeads.jpg[/img]

 

[CarlClassen]

The dish looks more like a cupel to me. I use a standard melting dish or one of the larger hard white ones.

From the looks of the left over slag, there was lots of copper in the material and little or no silver (no white residue around the rim).

The color of the cooled material also does not appear to have been inquarted with silver, it typically has a silvery appearance with purple and dark colors mixed in. The texture is also wrong. The pieces should have come out more like cornflakes instead of random pieces of distorted alloy. You may be pouring the metal too fast from the looks of the material produced. Another possibility is that the metal was not fully molten.

Here's a photo of inquarted cornflakes made with silver:

[img:452:413]http://www.goldrecovery.us/images/275_inquarted.jpg[/img]

Steve

Hmm well its quite possible I got the wrong thing(cupel). When i went to the store to buy it the person who was working knew less then I do

Well i'm pretty sure i put the right amount of silver in. It was about half silver pellets. I did do the exact measurements though.

I think i poured too quickly and from too short a height. The metal hit the bottom of the stainless steel water jug i had.

Thanks for the picture. That helps me figure out when i have done it right.

Here is the type of silver i used.

[IMG:1024:768]http://i301.photobucket.com/albums/nn41/cdnArmy/Silver.jpg[/img]

 

[Harold_V]

It was just the amount of flame that came out. I think i had the acetylene on too high. You could say it "poped"

Popping is a sign of a back flash. It's loud, and usually blows out the torch. The flame from an oxy/acet torch is, indeed, a bit intimidating. I used natural gas and oxygen instead, which yields a considerably softer (and cooler) flame.

I see that since I'm not using the cutting tip i don't install it at all.

That's correct. The welding tips screw on the body directly, and the portion with the lever is removed. Once you have it down to that assembly, you can easily adjust the oxygen/acetylene for the type of flame you need. The main body has only two valves, while the cutting torch includes a third valve. it's an oxygen valve. I suggest you use the largest tip and run it at lower pressure. That will yield a volume of heat without excessive velocity. Blowing the gold out of the dish when you melt gold powder is a real possibility. When you melt the powder, hold the torch well back and allow the feather at the tip of the flame to melt the surface of the powder. Move closer only when it has been well melted. Otherwise you'll lose some values. Be advised that melting the powder is usually the source of small losses. You'll see the occasional flash, which is generally a miniscule ball of gold flying out of the dish. I melted in a container and recovered most of the losses as tiny gold balls.

Well it was 10k and 14k with silver used for inquartination. The material I got looks gold with purple.

The color really troubles me. I don't recall ever having results like you achieved. What I'm thinking is that something you melted wasn't what you think it was. Did you find it wouldn't melt easily? Did you continue to heat the material after it was molten? I don't understand why there's so much dark material in the flux---a sign that you either super heated the material, or you melted something that wasn't a gold alloy. Was the gold (I'm assuming it was gold) a strange color? Blue or purple gold, in other words? Gold is normally yellow, white or rose colored, with green gold included on a limited basis. The elements that make gold purple or blue can be troublesome------which is why I ask.

Harold commented:

That's a melting dish, not a crucible. They are not the same thing.

Oh, whats the difference?

Crucible are cylinders, or modified cylinders. The common type is what is referenced as a bilge crucible. It is widest at roughly the mid point, with a small base and slightly smaller opening at the top than the bilge diameter. They are also made as a true cylinder, or a simple taper, with the top the largest, tapering down to a more narrow base. In almost all cases, they are taller than they are wide, and will contain a large amount of material. They can be made of clay, but are more commonly made of graphite and clay mixed, or silicon carbide. They are normally used in conjunction with a furnace of sorts----they do not lend themselves well to torch melting the way a dish does. Crucibles, for the record, come in a vast array of sizes. Some are no larger than a walnut, while others are large enough to contain hundreds of pounds of aluminum. Size, once they get above the miniatures, is based on their volume in aluminum. A #2 holds 2 pounds of aluminum, just as a #500 holds 500 pounds of aluminum.

I don't have an assayer's cone mold. Can i pour the flux mixture into water to extract the material that way?

That might work, but you'll work harder at finding the prills, assuming they don't agglomerate. The idea behind an assayer's mold is that the values collect at the bottom, with the slag on top. If the slag is fluid enough, all of the values collect in one place.

As an alternate, you might consider using a short piece of angle iron. If you can cut it at an angle, then weld a pair of plates on each end, you can make what would serve as a cone mold, only elongated, It need not be very large----you deal with small amounts when working with a melting dish. The one thing that would be important is that the angle iron have sufficient wall thickness to absorb the heat without getting over heated. Otherwise the values may solder to the mold. Assayers cone molds are made of heavy cast iron to avoid that problem. If you make a mold as I suggested, coat it with soot from your torch by lighting the torch with just acetylene turned on----then play the torch on the mold. It will coat instantly. Be sure you have preheated the mold, so no moisture collects. That's an open invitation for a small steam explosion when you pour the flux and recovered metal.

The pressure settings I suggested may not be proper for your torch---it might pay you to experiment a little.

Harold

 

[CarlClassen]

The color really troubles me. I don't recall ever having results like you achieved. What I'm thinking is that something you melted wasn't what you think it was. Did you find it wouldn't melt easily? Did you continue to heat the material after it was molten? I don't understand why there's so much dark material in the flux---a sign that you either super heated the material, or you melted something that wasn't a gold alloy. Was the gold (I'm assuming it was gold) a strange color? Blue or purple gold, in other words? Gold is normally yellow, white or rose colored, with green gold included on a limited basis. The elements that make gold purple or blue can be troublesome------which is why I ask.

I think there is a good chance I over heated it. It melted really easily. The gold was just plain yellow gold chains all marked.

The pressure settings I suggested may not be proper for your torch---it might pay you to experiment a little.
Harold

The pressure setting were perfect. With those and the max single torch head I got a perfect flame right away!

The rest of the information you gave is going to be very useful. Thank you for taking the time to respond in such detail.

 

[Harold_V]

I think there is a good chance I over heated it. It melted really easily. The gold was just plain yellow gold chains all marked.

Over heating could be the problem, but so, too, could the chance that the chains were not karat gold, but gold filled. In that case, you would have a preponderance of base metals, which would oxidize badly when over heated. If your yield comes up short of gold, that is likely what you may have melted. Chains can be tricky---they are marked only with an attached tab---and could easily be faked by unscrupulous individuals.

I mentioned the color. There is also the chance that you used an extremely oxidizing flame. It would have had a pale blue inner cone, and likely had a loud hissing noise. Such a flame will rapidly oxidize your metal. When melting gold, try to keep the flame ever so slightly reducing, displaying a hint of yellow.

The pressure setting were perfect. With those and the max single torch head I got a perfect flame right away!

Very good news! I think you're going to enjoy having the torch. They are capable of some serious temperature----around 6,000° F as I recall. Gold and silver alloys melt almost instantly under such a flame, so your work is cut short.

The rest of the information you gave is going to be very useful. Thank you for taking the time to respond in such detail.

Welcome. :wink:

Harold

 

[The Refiner49er]

Hey All-

I just wanted to put my two bits in on this subject.

If you have to use a cutting torch to melt your gold, what works as a safety to prevent operation of the oxygen lever is a wedge (wood or whatever) inserted between the lever and the body of the torch. This will eliminate the risk of unintentional blasting of the gold from the dish.

John

 

[Oz]

It is probably worth revisiting the oxy/acetylene cutting torch head again. As Harold very rightly pointed out, a Hoke torch with a tip like you have on an oxy/acetylene cutting torch is ideal as with melting PMs you will never need the lever for excess oxygen. These tips give high heat at low gas velocity saving you from blowing away and loosing fine PMs.

If you are sure that you will never want to weld or cut steel by all means buy a Hoke torch, but in my opinion it is nice to have the added versatility of being able to do steel work. Harold gave very good advice as to pressure ratios and the adjustment and look of the flame you want for melting PMs. Honemaster gives a good tip on using a wedge to disable the lever.

If you are setting up an oxy/acetylene torch for cutting you would start with all 3 valves closed on your hand piece. After setting the pressures on your regulators at the tanks (pressures are set significantly higher for cutting than welding or heating) you then fully open the green (oxygen) of the 2 knobs at the base of your handset. You then crack open the red valve at the base (acetylene) and light it with your striker. Then you crack open your 2nd green knob at the top of your handset. You adjust the top green and lower red knobs until you have a good heating flame. You then start to heat your steel until you start seeing some puddling where you want to start your cut and depress your lever. This will give you the full pressure you have available to you from the setting you have on your regulator on the oxygen tank. This extra oxygen actually burns the steel and blows the slag out of the bottom of the cut.

Now we are not doing this here but I thought it worth explanation as there are some just learning this equipment and it helps explain what the controls they have available to them do. You can see why the lever is to be avoided in melting precious metals.

As Harold has pointed out the tip is ideal here just not the cutting handset due to the risk of accidentally hitting the lever if inexperienced. Honemaster suggested you wedge it so it can’t be activated, I just keep the web of my hand under the lever. Each of you will have to decide whether or not you will ever want to work with steel. I for one would not want to live w/o this capability for about the same cost as a Hoke set-up. Just as Harold talked about making a quick cone mold from angle and plate for recovering the values from fluxes, you have the tools in hand to make quick work of it with oxy/acetylene.

Although I have not done it, I understand that you can run hydrogen through the same rig instead of acetylene which would be nice for platinum group metals. Maybe Harold can share some details on the use and advantages of hydrogen.

It would also be worth mentioning that a pair of flashback valves at the base of your handset and again at the output of your regulators at the tanks is a good idea and cheap insurance. It is not a great risk, I was even taught years ago to shut the acetylene of first to give the loud “crack” blowing the tips clear in the process but it is better to err on the side of caution. It is also worth noting that when you are done always shut the gasses off at the main tanks, relieve the pressure on the gauge springs by backing them off, and shut all the valves on your handset. In those positions you have 3 points of shut-off, have saved undue stress on your gauge springs, and the handset valves have less chance of corroding at the seat points being tightly mated.

 

[CarlClassen]

[

I don't have an assayer's cone mold. Can i pour the flux mixture into water to extract the material that way?

That might work, but you'll work harder at finding the prills, assuming they don't agglomerate.

Ok i used soda ash and reheated and poured. Does prills look like sand once seperated? My water container looks like it has "gold" sand on the bottom.

 

[Harold_V]

That may well be some of the material you melted originally. Prills are nothing more than tiny droplets of metal that don't combine to form a larger mass. Thick slag is one of the reasons they don't----or not enough time in the molten state to allow them to come together. There's not much you can do aside from heat the material long enough-----or to use a cone mold. Sorting the values from the junk will be a tough job. You might consider boiling the pieces in dilute sulfuric or HCl to eliminate the flux--------or simply re-melting everything with more soda ash and borax. Once molten, stir the dish and try to make the tiny button that should form come in contact with the other tiny bits. They'll readily join one another if they make contact.

I hope you see the wisdom of using a cone mold instead of pouring to water.

Harold

 

[donald236]

hey guys, I'll be honest, im dumb founded when it comes down to knowing the difference between the different gases for torches . so Ive read it or heard it some where that mapp gas is a real good source for melting gold . so i bought a torch kit . did i do good or bad :?: :?: :?:
thanks in advance

 

[Harold_V]

MAPP gas is expensive, but otherwise probably OK. Without oxygen it won't perform as well as you'd like, however. Probably impossible to melt platinum with one.

One of the best gasses you can choose is natural gas. Most Hoke torches are made to operate on the stuff, so all you need is an oxygen cylinder, regulator, and you're in business. I used a large Hoke torch to melt everything, including platinum. It's desirable to use a fuel that is low in free carbon when melting the platinum metals to avoid creating carbides. A hydrogen torch is ideal.

Harold

 

[donald236]

well the kit included the gas tank and the oxygen tank plus hoses and everything . even the stricker

 

[Harold_V]

If you have natural gas at your disposal, it might pay to see how it would run with your torch when the MAPP is exhausted. If it works, it will save you a ton of money.

Knowing you have oxygen makes a huge difference. You'll like the torch, you just may not like the cost of operation. I'd say you did just fine!

Harold